Telephone system.



II. L. HARRIS.

TELEPHONE SYSTEM.

APPLICATION FILED APII.26. |915.

1,298,339. Patented Mar. 25, 1919.

' INVENTOR. a Hanf@ Jhr/"Ils IIIIH y mmmq HISATTO UNITED sTATEs PATENT EEicE.

HARVEY I.. HARRIS, OF ELYRIA, OHIO, ASSIGNOR, BY MESNE ASSIGNMENTS, TO STROMBERG-CARLSON TELEPHONE MFG. CO., OF ROCHESTER, NEW YORK, A

CORPORATION OF NEW YORK.

TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented Mar. 25, 1919.

Application led April 26, 1915. Serial No. 23,814.

To all 'whom 'it may concern:

Be it known that I, HARVEY L. HARRIS, a citizen of the United States, residing at Elyria, in the county of Lorain and State of Ohio, have invented certain new and useful Improvements in Telephone Systems; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to improvements in telephone systems. In modern telephone practice, the systems comprise a main or central office, telephone lines leadinor to the ohce and means at the central oce for connecting the telephone lines together. The party desired is called by the application of what is known as automatic ringing current. In this practice, the operator sets a key, the ringing current is automatically turned on and operates the signal of the party desired, at stated intervals, the intervals during which the current is applied being known as ringing intervals and the intervals when the current is not applied being known as'silent intervals. The ringing current used is frequently of high voltage, or otherwise possesses characteristics which would injure the responding party if connected to his receiver, while his receiver is at the ear.

The principal object of my invention is to improve such systems by providing means for preventing the responding party connecting his receiver to the conductors connected to the source of ringing current during the ringing period.

Other objects of my invention and the invention itself will probably be better understood from a description of specific embodiments of the invention.

Figure l shows diagrammatically a telephone system which includes a private branch exchange.

Fig. 2 is a diagram showing a modilication of the system shown in FigQl.

Fig. 3 is a second diagram showing a second modification of the embodiment of the invention illustrated in Fig. l.

Fig. 4 is a detail of the apparatus shown at X and R10 in Fig. 1.

Referring now first to the embodiment shown in Fig. 1, at I is shown a substation,

at II a main or central station, here illustrated as a private branch exchange central station, which, in the embodiment illustrated in Fig. l, constitutes the party responding to the call. At IV is shown a substation upon the private branch exchange system, which is connected to the private branch exchange by the telephone line F.

The line B is provided with a substation set and with the usual calling and cut-oft' apparatus at the main station. Means are provided at the main station for connecting the lines together, here shown as a cord circuit. A circuit is shown for connecting the station II to the station of the responding party, here shown as a trunk circuit D. A second cord circuit E is provided at the private branch exchange for connecting together telephone lines or for connecting the trunk D with a subscribers line, such as the line F. Mechanism is provided for calling the party at the station III, which in the embodiment illustrated in Fig. 1 consists of ringing machines, commutators, ringing keys and ringing relays. A signal is provided at the station of the party called, here shown as consisting of a lamp L5.

lVhen the operator at the station II operates the ringing key J3', ringing current is conne'cted from a ringing generator I-I3 throucrh the commutator I, and the ringing relay t, to the plug P1, thence through the jack J1 to the device X, which operates, closing a switch in the circuit of the signal L5, which is operated to indicate to the party at station III that hc is being called. The ringing current is'applied at intervals, the periods between these intervals being known as the silent periods, both ringing and silent periods being determined by the commutator I3. Means are provided for preventing the party at III connecting the receiver of his telephone set M1 tothe circuit D when the ringing current is on the line. These means include a relay R10, a switch 1-2 and associate conductors and switches which will be explained more in detail in the description of the operation.

When the party at III responds, the listening key N will be operated, connecting the telephone set M1 with the plug P2, which, when inserted into the jack J2 Will close a switch 3`4 in the circuit of the relay Rm. The trunk strands, however, will not be completed.untilr the relay R10 is energized by current over the battery Q, and Bm cannot be energized as long as'the switchjl2 Vis open, and since this relay will belopenV during each of tliei'inging periods, it will not be possible to Yconnect the telephone set lVI1 through during a ringing period. I-Iowever, as soon as aringing period has terminated, the switch 1 2 will be closed, and the relay R10 operated. Then operated, the relay R10 will Vnot only complete the cir cuit VD, but will interrupt the circuit of the Vdevice X and automatically disconnect the ringing current from the telephone line.

The operation of the system is as f0llows: Assuming that the subscriber at station I desires to communicate with the station at IV, the receiver of the substation set Y at I is removed fromV the hook in the usual manner, whereupon the switch 54-6 is closed, completing a circuit through the line `relay R, which willinclude kthe contacts-of the cut-olf relay R1, the limbs or' tbelineB, the substation set at A, therelayR and the bat; tery Q1. The `relay R VVwillloe energized, .closing the switch Tf-8 in the circuit of the l line lamp L1 and causing the illumination of the lamp L1. Y This lamp is so located as to come under the observation of the op`erator at the main station II. LThe operator will answer the call by inserting the plug Pinto the jack J of the line B. Y

While I have shown plugs and jacks as va most VconvenientV forni r for 'making' `the connections, it isobvious that any suitable switching means may be. employed. Yrlhe ymeans here shown at the mainstation VII for connectingilines together consists of a cord circuit, though, of course, any suitable connecting means may be employed. I also illustrate suitable supervisory f signaling means in the cordl circuit, here consisting of relays R2, B3', Rl and 'R5 and supervisory V lamps L2 and L3 controlled by said relays in a manner well known. The relay R3 is controlled over a circuit which includes the cut-oli' relay B-the contacts of the plug and jack and a portion of one of the strandsof the cord circuit andthe battery QJ.'- The circuit of the relay R2 includes the battery Q, portions oit' the strand of the cord cir cuit, contacts of the plug P and jack J, the

' strandsof the line B and the telephone set A at the substation I. The Jfurther circuit arrangement provided for these relays and the operation of the relays are all well known and constitute no part of my invention, so that their operation will not be described in detail here. Y j

vThe operator at the station II will connect lier telephone set M to the line B through the agency of the listening key N1, and on learningV that communication is de-k sired with some party at the station III, or connectedV thereto, the plug P, will bein# 'serted intothe'jack J1.L Ringing current is then placed upon the circuit D, operating Y one of theseries of ringing keys, here'shown as J', J1', ,J2 andlJ, which 'will connect one of a series of'generators, h'ereshown as' H, H1, I-I2 and H3, each connected with one VVof a set of commutatore I, Il', I2 and I. Asl Y suining that the key 'J3' is operated, a master key S will be operated at thesanie time, completing then circuitof the ringing relay R-ivhich is yas* follows': ground 20dconductor V21-contacts ofthe master key S- conductor 22`relay B-T-'conductor 23'-con tacts 24 and 25-conductor 26-battery Q,V

torground at 27. The relay It, will be ener.- lgized, completing a locking circuit from ground 28 through the contacts 29 and $0- the contacts 31 and 32 of the relay R6. f The relay R,V also attracts Vits armatures V33 and 84, disconnecting the -plugP1 from ythetalking strands 40 and 41 of the cord circuit and Y,

connecting the plug P, tothe ringing leads. Ringing current will nowl operate over the following circuit: ground at 10', generator Hg-comniutatoiy I-conductor l2-'key Jgrelay Its-switch l50,-34-the tip of' the plug P14-the `tip spring of the jack tor 54-device Xfeondense'r -fcontacts 57 and .5d-conductor *58.conductor 59'-L spring 6O-4plug contactV 61econductor.62,-V relay R, -conductorl 26e-battery.; Qyrrto ground 27. The current Athrough this .cir cuit will not be sufficient tov operate Vthe relay R6, but will operate the device XV which will attract its armature 1,' raising e thecatch 65 and releasinguthe contact 66 which falls back andengages the contact 67, completing a circuit'for the lamp Li,V Y

and G6',

I3 is provided fwith two Y iio/ direct current in the battery @is connected 1 over the ringing circuit. Owing.r to the presence of the condenser 55 in this circuit, which bars the ow of current from the battery Q, the device X `will not be operatedl during the silent period. The Ylamp L, is in .f

such a position that itsgopera-tion willY be observed by the partyat the station VIII, who will respond to the sama-in the form of the invention illustrated by inserting the plug P2 into'the jack J2 and operating the listening-key N. .l/Vlien the plug is inserted into the jack, the switch 3 4 will beoperated through a physical connection .80 between the spring 4 Land thespring 81 of the jack.

This will close the switch 3-11 in the circuit of the relay R10. Another switch 1-2 is provided in this circuit which will be open, as shown, during the application of the ringing current. The switch 1 2 will be closed during the silent period, So as to complete the circuit of the relay R10. If the receiver of the set M1 is connected through the key N and the plug P2 and jack I2 to the ends 85 and 86 of the trunk during the ringing period, they will not be connected through to the station II because the relay R10 will not vbe operated. If, however, they are connected during the silent period, the relay R10 vwill be operated, or, if so connected to the conductors 85 and 86 during the ringing period, they will be connected through to the station II as soon as the ringing period has been interrupted. The circuit of the relay R1o will be as follows: R10-conductor 88- contacts 3 and a-conductor Sil-conductor S9-contacts 60-61-conductor 62-relay It-conductor 26S-battery Q., ground at 27-ground :at 74, section 7 3 vof the commutator I12-key J3-relay RG-contacts 50 and 34, the tip of the plug Pl-tip spring of jack ,If-conductor 5l-conductor 91- switch l-2-conductor 92 and back to relay R10. Vhen energized over this circuit, the relay R10 attracts its armatures 52 and 56, disconnecting the device X from the cond'uctors 51 and 59 and restoring, through means illustrated in Fig. 4.-, the member 66 to the catch 65. This will also energize the relay R6, which in turn interrupts the circuit of the relay R7 and completes the talking strands of the cord circuit C, so that the parties at II and III are now placed in communication.

If it is desired to secure a party connected to the private branch exchange, such as the subscriber at IV, the cord circuit E is operated in the Vusual manner, to effect such a connection, the usual test being made. The plug I4 is inserted into the jack J4 and the subscriber at IV rung. At the termination of the use ot the system, the operators will be notiied, through the use of suitable s upervisory signaling apparatus, all of which 1s old and well known, of the termination of the conversation, whereupon Vthe plugs will be withdrawn from the jacks and the system restored to normal.

In the modification shown in Fig. 2, the conta-ctsl and 2 in the circuit of the relay Rw. instead of being controlled by the device X, are controlled by a relay R20 in the circuit of said device. During the ringing period, both the device X and the relay Rm, will 'be operated, and the switch 1- 2 wlll be opened, preventing the energization of the relay R10 and the completion of the ringing circuit to the receiver of the set M1.

In the modification shown in Fig. 3 the circuit of the rel-ay R10 is local to one end of the circuit D. This circuit is as follows: ground at 200-conductor 20l-contacts 202-203-conductor 20arelay R10-conductor 205-contacts 2OG2O7-battery 20S-to ground at 209. This circuit is controlled -by the device X in the same manner as in the embodiment illustrated in Fig. 1 and it self-controls the connections in the same manner as in the embodiment shown in Fig. l. In the embodiment shown in Fig. 3 the combination apparatus shown in Fig. 4 is employed.

The operation of the apparatus shown in Fig. at will be apparent from the descriptions already given and from the illustration of that device.

IVhile I have illustrated `three embodiments of my invention, it will be apparent that it is broader than these modifications, and is capable of being incorporated in other embodiments. These modifications have been shown, not with the intention of limiting the invention thereto, but forthe purpose of illustrating thisv invention, it being apparent to those skilled in the art that many variationsl may be made from such embodiments, as well as from the details thereof, without departing from the scope of the invention which is set forth in the appended claims. 4

1. In a telephone system, the combination of a main station, link conductors therea't, a second station, circuit conductors connecting the main and second stations, a signal at the second station, a substation set at the Second station normally disconnected from said conductors, a source of current at the main station for causing the operation of the signal at the second station, means to break such current up into silent and active periods, means to automatically disconnect said source from said circuit conductors when said substation set is connected to said circuit conductors and means at the second station permitting said set to be connected to said conductors during a silent period and preventing the connection of said set to said conductors while said ringing current is connected thereto. 4

2. In a telephone system, the combination of a main station, means at the main station for connecting telephone lines together, a source of signaling current and means to connect said source of signaling current to said connecting means, a second telephone station, a circuit for connecting the main station and the second telephone station, a talking set'at the second station, a signal at the second station responsive to currents from the source of signaling current at the main station, apparatus at the main station for breaking the signaling current up into active and silent periods, means at the second telephone station for connecting the tors for connecting said stations together,

a 4source ofcalling current' at the calling station', means for automatically connecting said -fsource to said conductors including mechanism for interruptingthe Vcalling current andproducing ringing and silent periods, a signal at the .called station controlled ,by the ringingcurrentga substation set at thev called station, means' preventing the connection of the substation Aset to said conductors during aringing vperiod and apparatusor connecting-said set to said conductors during 'a'.silent period. 4:. Ina telephone system, the combination cfa calling stationand-a called station, conductors normally `interrupted at the outgoing4 Tend thereof' to `connect said kstations together, a source of 'calling c i'irrent,rmeans for connecting said sourceto' saidflconductors, including a continuously operating commutator/for interrupting lthe ioW of ringing current and breaking the timefof Vits operation up into silent and ringing periods, a telephone set4 at the calledstation and means for connecting said setto said' conductors, said means being loperative during a silent `period but` inoperativegduring a ringing .period` n f 5. Ina telephone system, Vthe combination of a'calling station, a called station, trunk conductors normally, interrupted at 'their outgoing ends connecting said stations, a

source of calling current at the calling station, means to applyrcalling current from said source to said conductors and means to prevent the completion of said conductors VWhile the calling current is applied thereto.

6. In a telephone system, the combination of a calling station, a called station .and trunk conductors .normally interrupted at their outgoing ends for-connecting said stationsy together, a source of calling current at the calling station,means to apply said current to said conductors, and apparatus for completing said conductors from one of said-stations to the other, said means being y inoperative to VVcomplete said connections While the calling current is applied to said conductors.

7 lIn a telephone system, theV combination of a calling station, a called station, a signal at the called station, a source of calling cur Vrent Vat thecalling stationfor causing the operation ofrsaid signal,trunk conductors normally interrupted at theiroutgoing endsy for connecting said stationstogether, means for applying. callingV current [from Vsaid source to said conductors for* theoperatiOn of said signal and means .for preventing 'the completion of vsaid conductors during the application of calliing current' tomidi-Coli; ductors.

8,. In a telephone system, .'tliecombination of a," calling.. station"A and agcalled station, trunk conductors normally interrupted v.at

their outgoing ends tofconnectsaidstations,

a signal at the called station, ia source of signaling current atl the calling station for causingfthe operation. of said signal over said conductors, means to apply current from saidr'source to saidv conductorsto cause the operation orv said signal, mechanism for complating said conductors from stationito-station, said mechanism being operative only ,when said signaling current :is not Iapp-lied to saidcondiictors. s 5 f 9. Ina telephone system, .the combination of a calling station, a called statioinconductors connecting said stations, normally interrupted contacts in said conductors, a relay controlling *saidy contacts, a source of'fcallV- ing currentat the calling station, means `to apply said calling current to said conductors, a lamp sign-alatthe called station controlled by the source of calling current, a'circuit for said relayaiid means .controlled by the call#V ing current controlling said circuit.

V10. In a telephone system, the combination of a calling stationfa called. station conductors -connectingsaid stations, normally interrupted contacts in said conductors, a relay controlling the saine, av signal at the called station, a source of signaling curentat the calling station for causing the `operation of said signahineans to .alp'pily' said signaling current to said conductors, a circuit for said relay, norinrally open .contacts in said circuit and inea-ns maintaining said` contacts open during the 1application of signaling current to said conductors, said'ineans being. controlled by said signaling current and operable to close the contacts in the relay cir.- cuit when the application of signaling cur,- rent to said `conductors is interrupted, and means to interrupt theV application of signaling current to said conductors.

11. In a telephone system, the combination of a calling. station, a called station, trunk conductors normally interrupted at'their outgoing ,ends for connecting said stations to- Y getlher, a signal ait Ithe called station,.a source 'of .calling current for causing the operation Y of said signal,.means to connect said source to said conductors including a constantly operating commutator for'breaking the application of signaling current to said con'- ductors Vup into silent periods kandringing periods, .andineans including .an alternating current relay yto 'complete' said conductors from station to station operable during a silent period but inoperative during a ringing peiiod.

12. In a telephone system, the combination of a calling station and a called station, normally interrupted conductors for connecting said stations together, a signal at the called station, a source of signaling current at the calling station for causing the actuation of said signal, means for connecting said source to said conductors including a commutator for interrupting the application of signaling current to said conductors and breaking the saine up into silent and active periods, normally open contacts in said conductors, a relay controlling said contacts, .a circuit for said relay and means controlled by the signaling current for maintaining said circuit open during the ringing period but closing the same during the silen-t period.

13. In a telephone system, the combination of a calling station, a called station, conductors connecting said stations, norm-ally open contacts in said conductors, an elcctromagnet controlling said contacts, a circuit for said electromagnet, a switch in said circuit, a signal Iat the called station, a source of calling current at the calling station for causing the actuation of said signal, an electromagnet at the called station responsive to the calling current controlling Said signal and the switch in the circuit of the rst named electromagnet, said second named electromagnet maintaining said switch open during the application of calling current but closing the same when the application of calling current to said conductors is interrupted.

14. In a telephone system, the combination of a main station, a private branch exchange station, a trunk -circuit for connecting said stations together, the strands of said trunk being normally interrupted at the outgoing ends thereof, a signal at the private branch exchange station, a source of signaling current at lthe main exchange station, means to cause the actuation of the signal at the private branch exchange station, including said source, and means to prevent the completion of the strands of the trunk circuit during the application of current from said source to the strands of said trunk circuit.

15. In a telephone system, the combination of a main exchange central station and a private branch exchange central station, a trunk circuit for connecting said stations together, a signal at the private branch exchange main station, a telephone set at the private branch exchange main st ation, a source of calling current at the main exchange central station, means to apply current from said source to said trunk, a commutator for interrupting the application of current from said source to said trunk, the current from said source controlling the operation of said signal, normally open contacts in said trunk and mechanism including a relay controlling said contacts for preventing the connection of the telephone receiver of said set to said trunk during the application of calling current to the trunk, said means permitting the connecting of said receiver to said trunk when the calling current is interrupted by said commutator.

16. In a telephone system, the combination of a calling station, a called station, conductors for connecting said` stations, a source of calling current at the calling station and means to apply the same to said conductors, a commutator for interrupting the application of current from said source to said conductors, a signal at the called station controlled by calling current from said source, a telephone set including a telephone receiver at the called station and mechanism inoperative during the application of the calling current to connect said receiver to said conductors, but operating to make such connection as soon as said commutator interrupts the application of the calling current.

17. In a telephone system, the combination of a main exchange central station, a private branch exchange central station, a trunk circuit for connecting the same, normally open switches in the strands of the trunk circuit, an electromagnet controlling said switches, a telephone set including a telephone receiver at the private branch exchange central station and means to connect said receiver to the strands of the trunk circuit, a signal at the private branch exchange central station, automatic signal current generating means at the main exchange central station, means to connect the same to the strands of the trunk circuit, apparatus for periodically interrupting the flow of current therefrom, a circuit for said first Vnamed electromagnet and a second electromagnet governed by the current from said automatic means controlling the circuit of the first named electromagnet and a circuit for said signal controlled by the second named electromagnet.

18. In a telephone system, the combination of a calling station, a called station, conductors for connecting said stations to gether, a source of calling current at the calling station, means to connect it to said conductors, a telephone set at the called station including a telephone receiver and means to connect said receiver to said conductors, normally open switches in said conductors and apparatus at the called station controlled by the calling current to prevent the closing of said switches while the calling current is applied to said conductors.

19. In a telephone system, the combination of a calling station, a called station, conductors for connecting said stations together, a

sourceof calling current at the calling station and means for automatically applying current from said source at regular intervals to'said conductors, a signal at the called station /eontr'ollecl by the current from said source,V normally open switches in said concdp'ies ofthisfpamt :hay b e obtained for Current to said conductors, said Ineens permitting the closlngof said switches When current from said source 1s not applied to said conductors. n

In Witness whereof, I have signed` myl name iny the presence 0I" two Witnesses, this 'Y 19 day of April, 1915. Y

HARVEY L. HARRIS.V

Witnesses:

GEO. A. SCOVILLE, F. L. CLARK.

ve cents each, by addiessing the' Commissione i Intenta, Washington, D. c. 

